1. Field of the Invention
The present invention relates to a method of fabricating an integrated circuit. More particularly, the present invention relates to a method of forming an etch mask using a single-layer resist during the production of a semiconductor integrated circuit device.
2. Description of the Prior Art
During semiconductor wafer processing, features of the semiconductor device are defined by a patterned etch mask. Multi-layer resist has been widely used as the etch mask in the fabrication process of the semiconductor integrated circuit devices. A multi-layer resist typically includes a patterning resist layer such as a photoresist, an interlayer such as a silicon layer and/or a silicon oxynitride layer, and a bottom resist layer such as an amorphous carbon film.
The photoresist is optically patterned according to a desired patterned on a photomask or reticle and then developed to remove the unexposed photoresist in positive lithography or exposed photoresist in negative lithography. The patterned photoresist then serves as a mask for a further step of etching the exposed interlayer and bottom resist layer in order to transfer the pattern from the patterned photoresist into the underlying interlayer and bottom resist layer. Thereafter, the patterned photoresist may be removed. An anisotropic dry etching process is then carried out to etch the material layer not covered by the patterned bottom resist layer to thereby form the circuit features.
However, one drawback of the above-described prior art is the difficulty of controlling critical dimension (CD) of the circuit features. Process variation and CD variation may be introduced during the optical lithographic process and/or during the dry etching process. Therefore, there is still a strong need in this industry to provide an improved method of fabricating an integrated circuit without the aforesaid shortcomings.
While the invention was motivated in addressing the above identified issues, it is in no way so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents.